The refined cotton is white cotton fibre made by boiling, bleaching and drying with the cotton linter as the material. The main technological process of the refined cotton is: material preparation→cotton opening→material feeding→boiling→delivery by dry method→bleaching→grinding→drying→package. Wherein, a lot of cotton dusts can be generated in the cotton opening process of the cotton linter, which not only affects the manual operation, but also affects the environment. Common dust collecting device is currently used, since the cotton dust generated in cotton opening is fine in flocculence, which is easy to gather into a cluster and is easy to block the filter screen at the air inlet of the dust collecting device, and although the cotton dust blocking the filter screen is usually cleaned, the dust collecting effect is still affected. Meanwhile, the cotton dust is discharged to the air after dust collecting treatment, which pollutes the environment.